U.S. patent application number 13/686646 was filed with the patent office on 2014-05-29 for shielding effectiveness determination.
This patent application is currently assigned to The Boeing Company. The applicant listed for this patent is The Boeing Company. Invention is credited to Kenneth P. Kirchoff, Dennis M. Lewis, Dennis Whetten.
Application Number | 20140149074 13/686646 |
Document ID | / |
Family ID | 50773992 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140149074 |
Kind Code |
A1 |
Whetten; Dennis ; et
al. |
May 29, 2014 |
SHIELDING EFFECTIVENESS DETERMINATION
Abstract
In one embodiment a method to evaluate a shielding effectiveness
of an enclosed structure, comprising collecting synthetic aperture
data from an electromagnetic transmission originating from within
the enclosed structure to generate a synthetic aperture dataset,
performing angular spectrum processing on the synthetic aperture
dataset to generate an angle of arrival dataset and determining a
shielding effectiveness parameter from the angle of arrival
dataset. Other embodiments may be described.
Inventors: |
Whetten; Dennis; (Edmonds,
WA) ; Lewis; Dennis M.; (Mill Creek, WA) ;
Kirchoff; Kenneth P.; (Redmond, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company; |
|
|
US |
|
|
Assignee: |
The Boeing Company
Chicago
IL
|
Family ID: |
50773992 |
Appl. No.: |
13/686646 |
Filed: |
November 27, 2012 |
Current U.S.
Class: |
702/182 |
Current CPC
Class: |
G06F 11/3466 20130101;
G01R 31/008 20130101; G01R 29/0835 20130101 |
Class at
Publication: |
702/182 |
International
Class: |
G06F 11/34 20060101
G06F011/34 |
Claims
1. A method to evaluate a shielding effectiveness of an enclosed
structure, comprising: collecting synthetic aperture data from an
electromagnetic transmission originating from within the enclosed
structure to generate a synthetic aperture dataset; performing
angular spectrum processing on the synthetic aperture dataset to
generate an angle of arrival dataset; and determining a shielding
effectiveness parameter from the angle of arrival dataset.
2. The method of claim 1, wherein collecting synthetic aperture
data from an electromagnetic transmission originating from within
the enclosed structure to generate a synthetic aperture dataset
comprises: positioning an RF transmitter within the enclosed
structure; positioning an RF receiver at a first position outside
the enclosed structure; and translating the RF receiver along a
predetermined path proximate the enclosed structure.
3. The method of claim 2, wherein collecting synthetic aperture
data from the enclosed structure to generate a synthetic aperture
dataset further comprises repeating the following operations:
positioning the RF receiver at a predetermined location along the
predetermined path proximate the enclosed structure; transmitting
an RF signal from the RF transmitter within the enclosed structure,
wherein the signal sweeps through a plurality of frequencies within
a predetermined frequency range; and collecting synthetic aperture
data in the RF receiver.
4. The method of claim 3, wherein the synthetic aperture data
comprises a two-dimensional array of complex values as a function
of transmit frequency and receiver location, the complex values
comprising: a magnitude difference between the RF signal
transmitted from within the enclosure and the RF signal received at
the receiver; and a phase difference between the RF signal
transmitted from within the enclosure and the RF signal received at
the receiver.
5. The method of claim 4, wherein performing angular spectrum
processing on the synthetic aperture dataset to generate an angle
of arrival dataset comprises: multiplying a one dimensional array
of the complex values for a single frequency by a transform factor
which is a function of a receiver location, an incident angle, a
frequency, and a window function.
6. The method of claim 5, wherein the angle of arrival dataset
comprises a two-dimensional array of power values at specific
frequencies of the RF signal transmitted from within the enclosure
against incidence angles of the RF signal received at the
receiver.
7. The method of claim 1, further comprising: applying a gating
function to the angle of arrival dataset; smoothing the power
values over a bandwidth range; and normalizing the power values to
one or more reference values.
8. A computer-based system to evaluate a shielding effectiveness of
an enclosed structure, comprising: a non-transitory memory; a
computer-based processing device coupled to the non-transitory
memory; and logic instruction stored in the non-transitory memory
which, when executed by the processing device, configures the
processing device to perform operations, comprising: collecting
synthetic aperture data from an electromagnetic transmission
originating from within the enclosed structure to generate a
synthetic aperture dataset; performing angular spectrum processing
on the synthetic aperture dataset to generate an angle of arrival
dataset; and determining a shielding effectiveness parameter from
the angle of arrival dataset.
9. The computer-based system of claim 8, further comprising: an RF
transmitter positioned within the enclosed structure; an RF
receiver positioned at a first position outside the enclosed
structure; and a linear actuator to translate the RF receiver along
a predetermined path proximate the enclosed structure.
10. The computer-based system of claim 9, wherein collecting
synthetic aperture data from an electromagnetic transmission
originating from within the enclosed structure to generate a
synthetic aperture dataset comprises: positioning the RF receiver
at a predetermined location along the predetermined path proximate
the enclosed structure; transmitting an RF signal from the RF
transmitter within the enclosed structure, wherein the RF signal
sweeps through a plurality of frequencies within a predetermined
frequency range; and collecting synthetic aperture data in the RF
receiver.
11. The computer-based system of claim 10, wherein the synthetic
aperture data comprises a two-dimensional array of complex values
as a function of transmit frequency and receiver location, the
complex values comprising: a magnitude difference between the RF
signal transmitted from within the enclosure and the RF signal
received at the receiver; and a phase difference between the RF
signal transmitted from within the enclosure and the RF signal
received at the receiver.
12. The computer-based system of claim 8, wherein performing
angular spectrum processing on the synthetic aperture dataset to
generate an angle of arrival dataset comprises: multiplying a one
dimensional array of the complex values for a single frequency by a
transform factor which is a function of a receiver location, an
incident angle, a frequency, and a window function.
13. The system of claim 12, wherein the angle of arrival dataset
comprises a two-dimensional array of power values at specific
frequencies of the RF signal transmitted from within the enclosure
against incidence angles of the RF signal received at the
receiver.
14. The system of claim 8, further comprising logic instruction
stored in the non-transitory memory module which, when executed by
the processing device, configures the processing device to perform
operations, comprising: applying a gating function to the angle of
arrival dataset; smoothing the power values over a bandwidth range;
and normalizing the power values to one or more reference
values.
15. A computer program product comprising logic instructions stored
in a non-transitory memory module which, when executed by a
processing device, configures the processing device to evaluate a
shielding effectiveness of an enclosed structure by performing
operations, comprising: collecting synthetic aperture data from an
electromagnetic transmission originating from within an enclosed
structure to generate a synthetic aperture dataset; performing
angular spectrum processing on the synthetic aperture dataset to
generate an angle of arrival dataset; and determining a shielding
effectiveness parameter from the angle of arrival dataset.
16. The computer program product of claim 15, wherein collecting
synthetic aperture data from an electromagnetic transmission
originating from within the enclosed structure to generate a
synthetic aperture dataset comprises: positioning an RF receiver at
a predetermined location along a predetermined path proximate the
enclosed structure; transmitting an RF signal from an RF
transmitter within the enclosed structure, wherein the signal
sweeps through a plurality of frequencies within a predetermined
frequency range; and collecting synthetic aperture data in the RF
receiver.
17. The computer program product of claim 16, wherein the synthetic
aperture data comprises a two-dimensional array of complex values
as a function of transmit frequency and receiver location, the
array of complex values comprising: a magnitude difference between
the RF signal transmitted from within the enclosure and the RF
signal received at the receiver; and a phase difference between the
RF signal transmitted from within the enclosure and the RF signal
received at the receiver.
18. The computer program product of claim 15, wherein performing
angular spectrum processing on the synthetic aperture dataset to
generate an angle of arrival dataset comprises: multiplying a one
dimensional array of the complex values for a single frequency by a
transform factor which is a function of a receiver location, an
incident angle, a frequency, and a window function.
19. The computer program product of claim 18, wherein the angle of
arrival dataset comprises a two-dimensional array of power values
at specific frequencies of the RF signal transmitted from within
the enclosure against incidence angles of the RF signal received at
the receiver.
20. The computer program product of claim 15, further comprising
logic instruction stored in the non-transitory memory module which,
when executed by the processing device, configures the processing
device to perform operations, comprising: applying a gating
function to the angle of arrival dataset; smoothing the power
values over a bandwidth range; and normalizing the power values to
one or more reference values.
Description
FIELD OF THE DISCLOSURE
[0001] This invention relates to testing and evaluation techniques
for radiofrequency (RF) shielding in enclosed structures, and more
particularly to objects and to systems and methods to determine
shielding effectiveness of structures such as aircraft.
BACKGROUND
[0002] Various regulatory bodies, e.g., the Federal Aviation
Administration (FAA) maintain standards for shielding RF emissions
from aircraft and require aircraft to be tested periodically for
compliance with the standards. Existing test methods require high
RF transmission power to achieve sufficient dynamic range to
measure shielding effectiveness. Such high RF transmission power
require expensive amplifiers which can limit the availability of
frequency spectrum required for the test. The limitations on
frequency spectrum available can limit the accuracy of shielding
effectiveness tests. Accordingly, systems and methods to test
enclosed structures for RF shielding effectiveness may find
utility.
SUMMARY
[0003] In one embodiment there is provided a method to evaluate a
shielding effectiveness of an enclosed structure, comprising
collecting synthetic aperture data from an electromagnetic
transmission originating from within the enclosed structure to
generate a synthetic aperture dataset, performing angular spectrum
processing on the synthetic aperture dataset to generate an angle
of arrival dataset and determining a shielding effectiveness
parameter from the angle of arrival dataset.
[0004] In another embodiment there is provided a computer-based
system to evaluate a shielding effectiveness of an enclosed
structure, comprising a non-transitory memory, a computer-based
processing device coupled to the non-transitory memory and logic
instruction stored in the non-transitory memory module which, when
executed by the processing device, configures the processing device
to perform operations, comprising collecting synthetic aperture
data from an electromagnetic transmission originating from within
the enclosed structure to generate a synthetic aperture dataset,
performing angular spectrum processing on the synthetic aperture
dataset to generate an angle of arrival dataset, and determining a
shielding effectiveness parameter from the angle of arrival
dataset.
[0005] In another embodiment there is provided a computer program
product comprising logic instructions stored in a non-transitory
memory module which, when executed by a processing device,
configures the processing device to evaluate a shielding
effectiveness of an enclosed structure by performing operations,
comprising collecting synthetic aperture data from an
electromagnetic transmission originating from within an enclosed
structure to generate a synthetic aperture dataset, performing
angular spectrum processing on the synthetic aperture dataset to
generate an angle of arrival dataset, and determining a shielding
effectiveness parameter from the angle of arrival dataset.
[0006] The features, functions and advantages discussed herein can
be achieved independently in various embodiments described herein
or may be combined in yet other embodiments, further details of
which can be seen with reference to the following description and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The detailed description is described with reference to the
accompanying figures.
[0008] FIG. 1 is a schematic, views of a system for shielding
effectiveness determination in accordance with some
embodiments.
[0009] FIG. 2 is a schematic illustration of a computing system in
which portions of a system for shielding determination may be
implemented according to embodiments.
[0010] FIGS. 3-7 are flowcharts illustrating operations in a method
for shielding determination, according to embodiments.
DETAILED DESCRIPTION
[0011] Described herein are exemplary systems and methods for
shielding effectiveness determination. Embodiments described here
provide systems, methods, and computer program products for
determining the shielding effectiveness of an enclosed structured,
e.g., an aircraft. In the following description, numerous specific
details are set forth to provide a thorough understanding of
various embodiments. However, it will be understood by those
skilled in the art that the various embodiments may be practiced
without the specific details. In other instances, well-known
methods, procedures, components, and circuits have not been
illustrated or described in detail so as not to obscure the
particular embodiments.
[0012] FIG. 1 is a schematic, views of a system for shielding
effectiveness determination in accordance with some embodiments.
Referring to FIG. 1, in one embodiment a system 100 comprises an
enclosed structure, e.g., an aircraft 110, an analyzer 120, and a
computer-based system 130 coupled to the analyzer. A transmitter
140 is positioned inside the aircraft 110. A receiver 150 may be
mounted to a track 160 which extends adjacent a portion of the
aircraft 110. A linear actuator 162 may coupled to the receiver 150
to translate the receiver 150 along a predetermined path proximate
the aircraft 110.
[0013] In some embodiments aircraft 110 may be embodied as
commercial aircraft, e.g. commercial jet. In alternate embodiments
aircraft 110 may be embodied as a military aircraft or the like.
Further, one skilled in the art will recognize that while the
enclosed structure is depicted herein as an aircraft, the specific
embodiment of the enclosed structure is not critical. The systems
and methods described herein may be applied to any enclosed
structure including land-based vehicles, waterborne vehicles,
buildings or other enclosures.
[0014] In some embodiments the analyzer 120 may be embodied as a
N5234A performance network analyzer commercially available from
Agilent in Santa Clara, Calif., USA.
[0015] FIG. 2 is a schematic illustration of a computing system 130
in which portions of a system for shielding determination may be
implemented according to embodiments. Referring to FIG. 2, in one
embodiment, system 130 may include one or more accompanying
input/output devices including a display 202 having a screen 204,
one or more speakers 206, a keyboard 210, one or more other I/O
device(s) 212, and a mouse 214. The other I/O device(s) 212 may
include a touch screen, a voice-activated input device, a track
ball, and any other device that allows the system 180 to receive
input from a user.
[0016] The system 180 includes system hardware 220 and memory 230,
which may be implemented as random access memory and/or read-only
memory. A file store 280 may be communicatively coupled to system
180. File store 280 may be internal to computing device 208 such
as, e.g., one or more hard drives, CD-ROM drives, DVD-ROM drives,
or other types of storage devices. File store 280 may also be
external to computer 208 such as, e.g., one or more external hard
drives, network attached storage, or a separate storage
network.
[0017] System hardware 220 may include one or more processors 222,
at least two graphics processors 224, network interfaces 226, and
bus structures 228. In one embodiment, processor 222 may be
embodied as an Intel.RTM. Core2 Duo.RTM. processor available from
Intel Corporation, Santa Clara, Calif., USA. As used herein, the
term "processor" means any type of computational element, such as
but not limited to, a microprocessor, a microcontroller, a complex
instruction set computing (CISC) microprocessor, a reduced
instruction set (RISC) microprocessor, a very long instruction word
(VLIW) microprocessor, or any other type of processor or processing
circuit.
[0018] Graphics processors 224 may function as adjunct processors
that manage graphics and/or video operations. Graphics processors
224 may be integrated onto the motherboard of computing system 200
or may be coupled via an expansion slot on the motherboard.
[0019] In one embodiment, network interface 226 could be a wired
interface such as an Ethernet interface (see, e.g., Institute of
Electrical and Electronics Engineers/IEEE 802.3-2002) or a wireless
interface such as an IEEE 802.11a, b or g-compliant interface (see,
e.g., IEEE Standard for IT-Telecommunications and information
exchange between systems LAN/MAN--Part II: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) specifications
Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz
Band, 802.11G-2003). Another example of a wireless interface would
be a general packet radio service (GPRS) interface (see, e.g.,
Guidelines on GPRS Handset Requirements, Global System for Mobile
Communications/GSM Association, Ver. 3.0.1, December 2002).
[0020] Bus structures 228 connect various components of system
hardware 228. In one embodiment, bus structures 228 may be one or
more of several types of bus structure(s) including a memory bus, a
peripheral bus or external bus, and/or a local bus using any
variety of available bus architectures including, but not limited
to, 11-bit bus, Industrial Standard Architecture (ISA),
Micro-Channel Architecture (MSA), Extended ISA (EISA), Intelligent
Drive Electronics (IDE), VESA Local Bus (VLB), Peripheral Component
Interconnect (PCI), Universal Serial Bus (USB), Advanced Graphics
Port (AGP), Personal Computer Memory Card International Association
bus (PCMCIA), a General Purpose Interface Bus (GPIB) and Small
Computer Systems Interface (SCSI).
[0021] Memory 230 may include an operating system 240 for managing
operations of computing device 208. In one embodiment, operating
system 240 includes a hardware interface module 254 that provides
an interface to system hardware 220. In addition, operating system
240 may include a file system 250 that manages files used in the
operation of computing device 208 and a process control subsystem
252 that manages processes executing on computing device 130.
[0022] Operating system 240 may include (or manage) one or more
communication interfaces that may operate in conjunction with
system hardware 120 to transceive data packets and/or data streams
from a remote source. Operating system 240 may further include a
system call interface module 242 that provides an interface between
the operating system 240 and one or more application modules
resident in memory 230. Operating system 240 may be embodied as a
UNIX operating system or any derivative thereof (e.g., Linux,
Solaris, etc.) or as a Windows.RTM. brand operating system, or
other operating systems.
[0023] In various embodiments, the system 130 may be embodied as a
personal computer, a laptop computer, a personal digital assistant,
a mobile telephone, an entertainment device, or another computing
device.
[0024] In one embodiment, memory 230 includes one or more logic
modules embodied as logic instructions encoded on a tangible, non
transitory memory to impart functionality to the system 280. The
embodiment depicted in FIG. 2 comprises a data collection module
262, and an analysis module 266 Additional details about the
process and operations implemented by these modules are described
with reference to FIGS. 3-7 below.
[0025] In operation, the computer based system 130 may be employed
to determine a shielding effectiveness of an enclosed structure,
e.g., an aircraft 110. In brief overview, In embodiments described
herein an RF transmitter may be positioned within an aircraft and
an RF receiver may be positioned outside the aircraft and
configured to move along a predetermined path to a plurality of
locations. At each location the transmitter transmits an RF signal
which sweeps through a plurality of frequencies within a
predetermined frequency range. Information about the magnitude and
phase of the RF signal and the RF signal received by the receiver
are provided to an analyzer. A computer-based system coupled to the
analyzer receives data from the analyzer and processes the data to
determine a shielding effectiveness of the aircraft 110.
[0026] In greater detail, and referring to FIG. 3, in some
embodiments a method to evaluate a shielding effectiveness of an
enclosed structure comprises collecting synthetic aperture data
(operation 310) from an electromagnetic transmission originating
from within the enclosed structure to generate a synthetic aperture
dataset, performing angular spectrum processing (operation 315) on
the synthetic aperture dataset to generate an angle of arrival
dataset, optionally applying a gating function to the angle of
arrival dataset (operation 320) and determining (operation 325) a
shielding effectiveness parameter from the angle of arrival
dataset. These operations will be described in greater detail with
reference to FIGS. 4-7. In some embodiments the operations depicted
in FIG. 4 may be implemented by the data collection module 262,
while the operations depicted in FIGS. 5-7 may be implemented by
the analysis module 266.
[0027] FIG. 4 is a flowchart illustrating operations in the method
to collect synthetic aperture data (operation 310) in accordance
with some embodiments. Referring to FIG. 4, at operation 410 a
vector network analyzer (VNA) sweep is triggered. As described
above, in a test environment an RF transmitter is positioned within
the enclosed structure and an RF receiver is positioned at a first
position outside the enclosed structure, e.g., on track 160. During
a VNA sweep the RF transmitter transmits an RF signal from within
the enclosed structure, wherein the signal sweeps through a
plurality of frequencies within a predetermined frequency range. By
way of example, RF transmitter 140 may transmit an RF signal that
sweeps through a frequency range between 500 MHz and 20 GHz.
[0028] Synthetic aperture data from the signal transmitted from the
transmitter 140 is then collected. By way of example, in some
embodiments the transmitter 140 and the receiver are coupled to
analyzer 120 and to computer-based system 130. The transmitter 140
provides the analyzer 120 and computer-based system 130 with
information about the magnitude and phase of the signal transmitted
by the transmitter 140. Similarly, the receiver 150 provides the
analyzer 120 and computer-based system 130 with information about
the magnitude and phase of the signal received by the receiver 150.
Using this information at least one of the analyzer 120 or the
computer-based system 130 may determine a magnitude difference
between the RF signal transmitted from within the enclosure by the
transmitter 140 and the RF signal received at the receiver 150 and
a phase difference between the RF signal transmitted from within
the enclosure by the transmitter 140 and the RF signal received at
the receiver 150. This data may be stored (operation 415) in a
synthetic aperture data table 450 which may reside in a
computer-readable memory medium, e.g., memory 230 and/or file store
280 of system 130.
[0029] The linear actuator 162 then moves the receiver (operation
420) from a first position on the track 160 to a second position,
different from the first position, and if the receiver is not at
the end of the track (operation 425) then the transmitter is
activated again. Thus, operations 410-420 define a data collection
process which is repeated at a plurality of locations along the
track to construct a synthetic aperture data table 450.
[0030] FIG. 5 is a flowchart which illustrates one embodiment of a
method for angular spectrum processing (operation 315), according
to embodiments. By way of overview, in some embodiments the
synthetic aperture data stored in table 450 may be converted to
angle of arrival data by perform a mathematical transform over the
physical dimension to convert it to the angular dimension,
resulting in a 2-dimensional array of complex values as a function
of frequency and incident angle. Referring to FIG. 5, at operation
510 a first frequency point is selected from the frequencies in the
synthetic aperture data table 450, and at operation 515 an incident
angle is selected from an incident angle list.
[0031] At operation 520 the angle of arrival data is determined for
the combination of the selected frequency and incidence angle. By
way of example, in some embodiments a transform factor, t, is
determined as a function of physical location, x, incident angle,
.theta., frequency, f, the speed of light, c, and window, w:
t ( x f .theta. ) = w ( x ) ? ? indicates text missing or illegible
when filed EQ 1 ##EQU00001##
[0032] Exemplary windowing functions, w, include rectangular,
Chebyshev, Hamming, etc., which may be used to reduce sidelobe
levels without compromising the signal. The use of windowing
functions is optional and the process works without explicitly
using any window function.
[0033] Next the one-dimensional array of data determined by the
transform factor function (EQ 1) is multiplied by the
one-dimensional array data and summed, as indicated in Equation 2
to generate an angle of arrival value for a single incident angle
and frequency. EQ 2:
AoA
Value(.theta..sub.n,f.sub.m)=(d(f.sub.m,x.sub.0)*t(x.sub.0,f.sub.m,.-
theta..sub.n)+d(f.sub.m,x.sub.1)*t(x.sub.1,f.sub.m,.theta..sub.n)+d(f.sub.-
m,x.sub.2)*t(x.sub.2,f.sub.m,.theta..sub.n)+ . . . )
[0034] If, at operation 525, there are more incident angles to
determine then control passes back to operation 515. Similarly, if
at operation 530 there are more frequencies to determine then
control passes back to operation 510. This process is repeated for
every frequency and incident angle. Thus, operations 510-530 define
a data transform process which transform the data in the synthetic
aperture data table 450 to angle of arrival data in the angle of
arrival dataset 550 which may reside in a computer-readable memory
medium, e.g., memory 230 and/or file store 280 of system 130.
[0035] FIG. 6 is a flowchart which illustrates one embodiment of a
method for angle gating (operation 320), according to embodiments.
By way of overview, in some embodiments shielding failures at a
known incident angle may be omitted from shielding effectiveness
values by gating the angular spectrum. Referring to FIG. 6, at
operation 610 one or more incident angles to gate are received. By
way of example, in some embodiments a test operator may input
incident angles to gate. At operation 615 a gating function is
generated, and at operation 620 the gating function is applied to
the angle of arrival data set.
[0036] FIG. 7 is a flowchart which illustrates one embodiment of a
method for shielding effectiveness processing (operation 325),
according to embodiments. At operation 710 the shielding data may
be smoothed over a relevant bandwidth range. At operation 715 a
shielding effectiveness parameter may be determined by comparing
the measured values to reference values for test locations and
frequency combinations (i.e., reference-measured=shielding
effectiveness parameter). Suitable Reference values may be
generated by either testing the same condition without the
structure, or through analysis and/or simulation. The shielding
effectiveness parameter may be provided to a human operator using
the system or to another evaluation program used to evaluate the
aircraft 110.
[0037] Reference in the specification to "one embodiment" or "some
embodiments" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least an implementation. The appearances of the
phrase "in one embodiment" in various places in the specification
may or may not be all referring to the same embodiment.
[0038] Although embodiments have been described in language
specific to structural features and/or methodological acts, it is
to be understood that claimed subject matter may not be limited to
the specific features or acts described. Rather, the specific
features and acts are disclosed as sample forms of implementing the
claimed subject matter.
* * * * *